caa a22 4500 46582644X CHVBK 20180323112150.0 cr unu---uuuuu 170327e19900401xx s 000 0 eng 10.1007/BF00258769 doi (NATIONALLICENCE)springer-10.1007/BF00258769 The effects of pH and temperature on the kinetic properties of skeletal muscle lactate dehydrogenase from anuran amphibians [Elektronische Daten] [P. Mendiola, J. De Costa] Summary: Muscle LDH activities were measured in two anuran amphibians with different behaviour and ecology, Rana perezi and Bufo calamita. Both pyruvate reduction and lactate oxidation were measured at temperatures of 15, 20 and 30°C, and at pH 7.0, 7.4, and 8.0. Pyruvate and lactate muscle concentrations were determined in individuals at rest and after exercise. R. perezi muscle used anaerobic glycolysis during 3 min of exhaustive exercise, with rising pyruvate and lactate concentrations. Enforced walking for 30 min caused high variability in lactate concentration in B. calamita muscle. Temperature and pH changes affected apparent Km values for pyruvate. When these factors varied simultaneously, enzyme affinity tended not to change. Thus, the thermodynamic effect on pyruvate reduction activity is high, especially at physiological substrate concentrations. In contrast, lactate oxidation activity tended to stabilize when temperature and pH varied jointly. Inhibition by substrate, pyruvate or lactate, seemed to have no importance in vivo. During exercise there was a rise in pyruvate concentration, and a probable decrease in pH, which increased pyruvate reduction reaction and decreased lactate oxidation, contributing to lactate accumulation in Rana perezi muscle. B. calamita muscle did not show pyruvate increase after exercise and its LDH was less dependent on pH at physiological concentrations. Pyruvate reduction rate did not therefore increase. R. perezi muscle enzyme had features of anaerobic LDH while B. calamita LDH muscle was more similar to mammalian heart enzyme, with differences in accordance with the different behaviour of these anurans. Springer-Verlag, 1990 Lactate dehydrogenase nationallicence Muscle nationallicence Anuran amphibians nationallicence Temperature nationallicence pH nationallicence LDH : lactate dehydrogenase nationallicence Mendiola P. Depto. Fisiología y Farmocología, Fisiología Animal, Facultad de Biología, Universidad de Murcia, 30 100, Espinardo, Spain aut De Costa J. Depto. Fisiología y Farmocología, Fisiología Animal, Facultad de Biología, Universidad de Murcia, 30 100, Espinardo, Spain aut Journal of Comparative Physiology B Springer-Verlag 160/1(1990-04-01), 105-111 0174-1578 160:1<105 1990 160 360 https://doi.org/10.1007/BF00258769 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00258769 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mendiola P. Depto. Fisiología y Farmocología, Fisiología Animal, Facultad de Biología, Universidad de Murcia, 30 100, Espinardo, Spain aut NATIONALLICENCE 700 1- De Costa J. Depto. Fisiología y Farmocología, Fisiología Animal, Facultad de Biología, Universidad de Murcia, 30 100, Espinardo, Spain aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer-Verlag 160/1(1990-04-01), 105-111 0174-1578 160:1<105 1990 160 360 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer